1. Field of the Invention
The present invention relates to a structure of engine mounting, and more particularly, to a structure of engine mounting, in which the roll mount is installed on a pitch axle, unlike the traditional torque roll supporting method, so that the unbalanced exciting force in the direction of the pitch is offset and the NVH (Noise Vibration Harshness) of the vehicle is improved.
2. Description of Related Art
As the vehicle operates, the noise and the vibration are bound to be created. However, recently, as the technologies applied to vehicles progress and the demand for vibration and noise control among the consumers is increasing, there have been constant attempts to analyze the noise, the vibration and the harshness coming from the vehicle, in order to maximize the comfortability of passengers. Also, interpreting NVH helps come up with criteria to estimate the level of noise and vibration generated as well as of their reduction.
The phenomenon of the vibration generated in the vehicle includes the pitching of the car body when starting or stopping a car, the vibration of the car body when idling, the vibration of the car body and the noise of harshness when the engine runs at a high speed, the vibrations caused by the bumpiness of the road, the pitching of the car body in case of overloading, the impact due to giving the vehicle a rapid change when taking off or shifting gears, and the interference and damage caused by excess displacement. The main cause for such vehicle vibration is the vibration of the engine as well as the impact conveyed from the road while the vehicle is moving.
Examples of the vehicle vibrations are, when the frequency is low (below 20 Hz), the power plant vibration caused by the torque changes, the inertial force and a couple of forces according to the rotation movement of the crankshaft in case of the low-speed revolving of the engine, the vibration of the car body caused by the unbalancedness when the tires are rotating, the vibration of the car body through the suspension according to the profile of the road surface, and the power plant vibration caused by a couple of forces and the thrust due to the joint angle of the actuating system, and when the frequency is high (above 20 Hz), the power plant vibration according to the rotation movement of the crankshaft in case of the high-speed revolving of the engine, the vibration caused by the engagement of the gears inside the transmission, the vibration of the cylinder block at the time of combustion, the vibration of the moving valve system of the engine, the bending vibration and the twisting vibration of the crankshaft, and the bending vibration and the twisting vibration of the power plant.
In order to decrease the vibration of the vehicle mentioned above, various forms of mount have been used, generally being installed between the origin of the vibration such as the engine or transmission of a vehicle and the car body, to control vibration and noise so that they are not conveyed to the car body. Also, a TM mount is used in order to prevent the motive power generated in the engine to be conveyed to the powertrain or the transmission, which results in noise and vibration.
According to the prior art, the torque roll axis supporting method was usually used, and in the torque roll axis supporting method, the powertrain rigid body mode (Roll: powertrain rotation with respect to the X-shaft, Pitch: powertrain rotation with respect to the Y-shaft, Yaw: powertrain rotation with respect to the Z-shaft) is generated in three different directions of X-axis, Y-axis and Z-axis when the engine is accelerated, and the engine mount and the TM mount are set up on the torque roll axis in order to minimize the noise and vibration generated by the powertrain rigid body mode in the vehicle, and the roll mount is loaded on the small part of the engine.
However, the structure of mounting by this torque roll axis supporting method has a huge disadvantage in terms of offsetting the unbalanced exciting force of the pitch element generated besides the roll moment (e.g. rotational force and vibration around the roll axis) when a three-cylinder engine is loaded. In other words, unlike in a four-cylinder engine, the moment element of a three-cylinder engine has the unbalanced exciting force in the directions of Pitch and Yaw, so the structure of the mounting of a three-cylinder engine has disadvantages in terms of reducing the exciting force in comparison to the structure of the mounting of a four-cylinder engine.
Therefore, there is a need to develop a structure for an engine mounting, which can improve the NVH performance by reducing the additional unbalanced exciting force in the direction of Pitch in a three-cylinder engine.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.